My idea is that if you make a container with a vacuum greater than the absolute vacuum would have such an inner strength, thus negating the force of gravity, making the object float in the air. So it could make aircraft safer than the present.

You are right, but you and many, forgive that the wall of container is made by matter. I belive that the force inside is opposite the gravite. This force is directed toward the center, so if we make a suction at the center, the force would work in favor.